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Prove that : cos 4x = 1 - 8 sin^2 x cos^...

Prove that : `cos 4x = 1 - 8 sin^2 x cos^2 x`.

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Taking LHS
`cos4x`
We know
`cos2x=2cos^2x−1`
...
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NCERT ENGLISH-TRIGONOMETRIC FUNCTIONS-All Questions
  1. Prove that: cot x cot 2x - cot 2x cot 3x - cot 3x cot x = 1

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  2. Prove that:cos6x=32cos^6x-48cos^4x+18cos^2x-1

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  3. Prove that : cos 4x = 1 - 8 sin^2 x cos^2 x.

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  4. Find sinx/2,cosx/2 and tanx/2of the following : cotx=-1/3, x in quad...

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  5. Find sinx/2,cosx/2and tanx/2 of the following : tanx=-4/3, x in quadra...

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  6. Two trees, A and B are on the same side of a river. From a point C in ...

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  7. A tree stands vertically on a hill side which makes an angle of 15^0 w...

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  8. Two ships leave port at the same time. One goes 24 km per hour in the ...

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  9. For any triangle ABC, prove that(b^2 - c^2) cotA + (c^2 - a^2) cotB + ...

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  10. For any triangle ABC, prove that(b^2-c^2)/(a^2)sin2A+(c^2-a^2)/(b^2)si...

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  11. For any triangle ABC, prove that acosA+bcosB+c cosC=2asinBsinC

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  12. For any triangle ABC, prove that(cosA)/a+(cosB)/b+(cosC)/c=(a^2+b^2+c^...

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  13. In any triangle ABC, if a=18 , b=24 , c=30, findcosA, cosB, cosC

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  14. For any triangle ABC, prove that(a+b)/c=(cos((A-B)/2))/(sinC/2)

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  15. In any triangle ABC, if a=\ 18 , b=\ 24 , c=\ 30, findsinA, sinB, sinC

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  16. For any triangle ABC, prove thatsin(B-C)/2=(b-c) /a ( cosA/2)

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  17. For any triangle ABC, prove that(a-b)/c=(sin((A-B)/2))/(cos(C/2))

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  18. For any triangle ABC, prove that a(cosC-cos B)\ =\ 2\ (b - c)\ cos^2(A...

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  19. For any triangle ABC, prove thata(bcosC-c cosB)=b^2-c^2

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  20. For any triangle ABC, prove that(b+c)cos((B+C)/2)=acos((B-C)/2)

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